There are two common types of modern computer printers, inkjet and laser printers. Inkjet printers are the most common for home computer use. The inkjet printer consists of a printer body that holds and moves paper, and the inkjet printer cartridge that contains ink and a print head. The paper is moved from top to bottom by the printer, and the inkjet print cartridge is mounted on a carrier that moves horizontally and allows it to dispense ink in the appropriate patterns across the page.
The ink print cartridges are not simply reservoirs full of ink. These cartridges also contain the actual print head. See, for example, U.S. Pat. No. 5,675,367 to Scheffelin et al, which discloses an integrated print head along with a reservoir for holding ink. This configuration of the integrated print head and cartridge containing ink is the industry standard, and all of the major printer and cartridge manufacturers, including, but not limited to Dell, Hewlett-Packard, Epson, Brother, and Lexmark, use these types of inkjet cartridges.
The current business model for many of the manufacturer's of inkjet printers is to sell the printer relatively cheaply, and then make most of their money by selling replacement ink print cartridges. In general, inkjet printer manufacturers have structured their business model similar to the manufacturers of razor blades. They sell the printer (or razor) at very little profit, and reap most of the product profit from the sale of subsequent supplies (ink cartridges or razor blades). In recent years, however, the ink jet printer manufacturers have been loosing more and more of the profit from the sale of new or remanufactured ink jet cartridges to refillers. Refillers are either companies set up specifically to refill empty ink jet cartridges or individual consumers who refill their cartridges on their own. Companies that refill empty cartridges sell them for a lower price than new ones sold by the printer manufacturer. Individual consumers can purchase refill kits that will allow them to refill a cartridge multiple times for less than the cost of a single new ink cartridge. One Harvard Business School professor estimated that “private branded label offerings now constitute nearly 30 percent of the worldwide ink market.” (Professor Clayton M. Christensen, “Will Kodak's New Strategy Work?” by Clayton M. Christensen and Scott D. Anthony, Published on Forbes.com, Feb. 26, 2007.)
This business model has helped keep the cost of replacement printer inkjet cartridges (hereinafter “cartridges”) relatively high. As a result, a number of companies have developed, manufacture and sell compatible replacement cartridges. For example, most office supply stores such as Office Max, Office Depot and Staples, have generic or store brand replacement cartridges. Initially a number of printer manufacturers attempted to develop technology to prevent the use of non-genuine or non-branded replacement cartridges, but the courts struck that down. See, for example, Lexmark International, Inc. v. Static Control Components, Inc., 387 F.3d 522 (6th Cir. 2004). But even these “knock-off” replacement cartridges are relatively expensive, so there is still a financial incentive to find ways to refill existing cartridges.
While there are many different ways to refill an inkjet cartridge, there are three that are most common. The first involves simply drilling a small hole into the central reservoir of the cartridge and injecting ink with a syringe having a small diameter needle. The second involves dripping ink into the vent holes of the cartridge. The third involves subjecting the interior of the cartridge to a negative pressure by means of a vacuum device, and then putting either the print head portion or the vent holes of the cartridge into liquid ink, and allowing the ink to flow into the central reservoir of the cartridge due to the pressure differential. Examples of patents that disclose refilling methods include U.S. Pat. Nos. 5,199,470; 5,400,573; 5,546,830; 5,572,852; 5,819,627; 5,845,682; 6,347,863; and 6,971,740.
At least one method to prohibit the refilling of ink jet cartridges has already been patented. That method is described in U.S. Pat. No. 6,099,101 to Maurelli. The method described in the '101 patent involves placing a monitoring and disabling device inside the ink jet print head cartridge. When the print head has exceeded its useful life span, the disabling device disables the print head cartridge through the electrical discharge from capacitors that essentially burns out and renders the print nozzles permanently inactive. This patent describes the use of ink sensors to determine when the print head has exceeded its useful life. Another possible variation on this approach would be the incorporation of a “computer chip” within the ink cartridge that would “count” the number of times that one or more of the print head nozzles was energized. From that count the number of print drops from those nozzles would be known and thus some inference could be made on the amount of ink left in the cartridge. The cartridge could then be made inoperable after a certain number of drops were printed through communication of a specific instruction code to a printer processor. That scheme could be designed to enable the “chip” to be reset when the cartridge was remanufactured or refilled by an approved entity without destroying the cartridge. This is somewhat similar to the process disclosed in U.S. Pat. No. 6,325,495 to Foth, which incorporates a computer chip, or “smart button cell” that prevents the print head from functioning after a preset number of uses.
Both of these refill prevention methods involve the use of electronic or computer equipment. Unfortunately, virtually any electronic or computer fix can be bypassed by a skilled computer expert. There is a need, therefore, for a relatively inexpensive non-electronic method for the prevention of refilling of inkjet cartridges.